Conventionally, an industrial robot (hereinafter abbreviated as robot) using a parallel link mechanism has been known. This robot includes a base section that is a support base, a head section including an end effector, and a plurality of arms that each connect the base section and the head section. The respective arms are driven separately and in conjunction with each other by a motor mounted to the base section, so that the position or attitude of a head is changed. The head is mounted with the end effector that is activated with an actuator such as an electric motor or air cylinder, and various works are executed by the end effector.
In this type of robot, a cable or pipe for supplying power, air, or the like for driving the end effector is often wired point to point with a margin to a degree that does not cause interference with each arm or routed along each arm to be fixed to the arm by a fixing member such as a binding band. Recently, as disclosed in Japanese Patent Application Laid-open No. 2009-248288, for example, a technique in which an arm is configured of a hollow rod and the rod is utilized as an air pipe has been also proposed.
The robot using a parallel link mechanism is often used for applications in food products such as sorting of packaged food products. Therefore, due to hygienic reasons or the like, it is conceivable that an exposure of a cable or the like is prevented by forming an arm with a hollow rod and routing the cable or the like inside the rod. In the case of the robot using a parallel link mechanism, the robot may be driven at high speed and accompanied by a movement such as instantly changing the moving direction. In such a case, it is conceivable that an abnormal noise is caused by a cable or the like hitting the inner circumferential surface of the rod.